1. Field of the Invention
The present invention relates to a brushless motor.
2. Description of the Related Art
Conventionally, electric motors are used as driving sources of various types of apparatuses and products. For example, the motors are used as power assist sources for business machines, such as printers and copying machines, various kinds of home electric appliances, and vehicles, such as automobiles and power-assisted bicycles. In particular, brushless motors are sometimes used as the driving sources of movable parts with high operation frequency in the light of increased durability and reduced noise.
In a high-output brushless motor, the maximum torque required is large and therefore the induced voltage tends to be large. As a result, the motor rotating speed tends to be insufficient in a low-torque region. In the light of this, for example, the induced voltage needs to be made smaller for the purpose of increasing the motor rotating speed in the low-torque region. In order to enlarge the output range of the high-output brushless motor, the phase of the brushless motor needs to be controlled and it is vital that the position of a rotor be detected. In other words, in the brushless motor, the rotation position of the rotor needs to be detected by using a certain method and then the phase of the current flowing in a coil needs to be controlled.
To achieve this, proposed is a brushless DC (direct-current) motor comprised of a plurality of Hall elements for detecting the rotation position of a magnet rotor and a drive control circuit for supplying the drive current to an exciting coil based on the output timing with which a detection signal is outputted from the Hall elements (see Patent Document 1).